This disclosure relates to vehicle restraint devices, and in particular to a system and method for adaptively controlling vehicle restraint devices.
In passenger vehicles, passenger restraint systems employed for restraining passengers during an accident are designed to meet safety standards and assessment tests. Seat belts are typically simple retractable straps which hold the occupant in place. In a crash, the tension in the belt generally increases linearly with the amount of stretch imparted to it by the occupant. Thus, the tension in the belt is ever increasing which translates into increasing force levels imparted to the chest of the occupant. Since injuries are related to peak forces and accelerations sustained by occupants, this type of restraint is less than ideal.
A constant force retractor has a load limiting feature which eliminates this peak force application to the occupant. One such retractor is shown in U.S. Pat. No. 5,547,143, which is incorporated herein by reference.
A constant-force seat belt retractor system and air bag together create a restraint system which may be tuned to provide optimal restraint performance in a given crash situation for a given occupant. This system once tuned for a specific vehicle and occupant size will not account for the condition that various sized occupants require different restraint force levels for optimal protection. A system tuned for an average male at 35 mph may be more firm than is appropriate for a smaller, lighter occupant, while the system tuned for the average-sized person may have marginally adequate restraining capability to keep a rather heavy person from impacting the windshield or instrument panel.
Such lack of adaptability also involves several other factors, such as the rapidity of deployment of the air bag with correspondingly high deployment forces. Accidents less severe than the predetermined standards may cause vehicle occupants to experience different forces due to the inability of the system to recognize and adapt to different crash situations and occupant characteristics. A belted occupant may be more effectively restrained by a less firm air bag than is required for an occupant who is not wearing a seat belt.
The adaptive occupant restraint system and method is a significant improvement over the prior art as it is able to tailor occupant restraint during a crash to the specific occupant characteristics (weight, proximity to airbag, and seat belt usage) as well as to the crash severity.
A system for controlling adaptive vehicle occupant restraint devices uses a processor for receiving input signals from a plurality of sensors, for generating control parameters using a predetermined program, and for generating control signals from the control parameters to adaptively control the restraint devices during an accident.